Bone Cement Applicator with Retractable Mixing Rod
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Solution Overview
Problem
Conventional bone cement applicators for polymethylmethacrylate (PMMA) bone cements often result in air bubbles during mixing, leading to compromised mechanical properties, and require external vacuum pumps and separate extrusion devices, which complicate the process and increase the risk of leakage and contamination.
Innovation Solution
A closed prepack mixing system with an integrated extrusion device that stores and mixes PMMA bone cement powder and monomer liquid separately, using a mixing rod with a mixer to combine the components within the system without external vacuum, allowing for direct extrusion of the bone cement without additional devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional mixing methods with external vacuum pumps are used, then air bubbles can be prevented, but device complexity increases and leakage risk increases
Solution Approach 1:
The patent integrates the vacuum generation function directly into the applicator device by using the syringe plunger to create vacuum, eliminating the need for separate external vacuum pumps. The mixing and extrusion functions are also combined in a single integrated device, resolving the technical contradiction by merging multiple functions into one compact system.
Solution Approach 2:
The device uses its own components (syringe plunger, mixing rod, applicator body) to generate vacuum and perform mixing without requiring external equipment. The system is self-sufficient, creating its own vacuum environment and performing all mixing operations internally, which reduces device complexity while maintaining reliability.
2Ease of operation
If separate extrusion devices are used, then bone cement can be applied, but the process becomes more complex and contamination risk increases
Solution Approach 1:
The patent combines the extrusion function with the mixing and storage functions in a single integrated applicator device. The syringe mechanism serves both to mix the bone cement components and to extrude the mixed cement, eliminating the need for separate extrusion devices and simplifying the overall process.
Solution Approach 2:
The applicator device performs multiple functions: storing bone cement powder, holding monomer liquid, mixing the components, and extruding the mixed cement. This multi-functional design eliminates the need for multiple separate devices, reducing complexity and potential contamination points while maintaining ease of operation.
3Ease of manufacture
If mixing is done in open beakers, then components can be mixed, but air bubbles are enclosed and mechanical properties deteriorate
Solution Approach 1:
The patent creates a closed vacuum environment within the applicator device during mixing, preventing air from entering the bone cement mixture. The syringe-based vacuum system ensures that mixing occurs in an air-free environment, eliminating air bubble formation while maintaining simple mixing operations through the integrated device.
Solution Approach 2:
The patent introduces an intermediary vacuum environment created by the syringe plunger that mediates between the open atmosphere and the bone cement mixing process. This vacuum intermediary prevents direct contact between air and the mixing process, eliminating air bubbles while keeping the mixing operation simple and integrated into the applicator device.
4Ease of operation
If manual mixing with spatulas is used, then components can be combined, but air inclusions occur and mechanical properties are compromised
Solution Approach 1:
The patent replaces the traditional spatula-based mechanical mixing system with a syringe-based vacuum mixing mechanism. Instead of using spatulas that introduce air, the system uses controlled vacuum and internal mixing elements that eliminate air inclusions while maintaining ease of operation through the integrated applicator device.
Solution Approach 2:
The patent creates a closed vacuum environment within the applicator device during mixing, preventing air from entering the bone cement mixture. The syringe-based vacuum system ensures that mixing occurs in an air-free environment, eliminating air bubble formation while maintaining simple mixing operations through the integrated device.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution eliminates the need for external vacuum pumps and extrusion devices, reduces the risk of leakage and contamination, and ensures thorough mixing of the bone cement, improving its mechanical properties and simplifying the application process.
Implementation Method 1
a mixing rod (57) with a mixer (60) fastened to it, arranged in the internal space (61) of the cartridge (51)
Implementation Method 2
a dispensing plunger (12, 62) for expelling the mixed bone cement (48) from the internal space (11, 61) through the dispensing opening (16, 56)
Data Source
AI summary
A bone cement applicator comprising a cartridge with an internal space. The cartridge has a head with a dispensing opening for expulsion of bone cement, a dispensing plunger, a receptacle mobile in the cartridge, and a mixing rod with a mixer fastened to it and arranged in the internal space of the cartridge. The mixing rod is detachably connected, on a side opposite from the mixer, to a front side of the receptacle that faces the cartridge head. When the mixing rod is detached from the receptacle and the receptacle is propelled in the direction of the cartridge head the mixing rod can be pushed into the receptacle. A method is also disclosed for production of a bone cement using the bone cement applicator.